Conducting polymers have been used in a wide range of applications where they provide such advantages as light weight, high conductivity and electrochromic properties. Such properties render the conducting polymers suitable for a variety of applications including organic light emitting diodes (OLEDs), organic photovoltaic devices (OPVs), capacitors, and sensors.
Poly(3,4-ethylenedioxythiophene) (PEDOT) is a known conducting polymer exhibiting a high conductivities, ranging from 10−2 to 105 S/cm. As PEDOT is insoluble in many common solvents, it is prepared by template polymerization with a polyanion, poly(styrene sulfonic acid) (PSSA). PSSA is a charge-balancing dopant during polymerization in water which allows for the formation of a colloidal dispersion of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) or PEDOT-PSS. PEDOT-PSS is commercially available and has desirable properties, such as high stability in the p-doped form, high conductivity, good film formation, and excellent transparency in the doped state. PEDOT-PSS dispersed in water can be spin-coated to result in transparent films.
However, PEDOT-PSS lacks thermal stability at high temperatures. PEDOT-PSS can only be annealed at 180° C. for a few minutes and annealing beyond 200° C. causes a marked decrease in conductivity, rendering it an insulator rather than a conducting polymer. Therefore, PEDOT-PSS has limited use for high-temperature processing or high-temperature applications.
There remains a need in the art for conducting polymers having both high electrical conductivity as well as high thermal stability.